Scalloped Flexure Ring for Thermal Mismatch in High CTE Couplings

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Coupling structures with high and low coefficients of thermal expansion, such as metallic and ceramic structures, face thermal mismatch issues when rigidly joined, leading to high strains in the ceramic material, especially in elevated temperature applications.

Innovation Solution

A scalloped flexure ring with a ring body having a first straight edge and a second scalloped edge, featuring spaced-apart ring fingers that provide radial flexibility, allowing for relative thermal expansion and contraction between structures with different CTEs, thereby minimizing thermal stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid joining is used to couple high CTE and low CTE structures, then structural strength and stability are improved, but thermal mismatch induces high strains and stresses in the ceramic structure

Engineering Contradiction:
Improvestructural strengthVSAvoidthermal stress
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The coupling structure transitions from a rigid static connection to a dynamic flexible connection. The flexure ring with scalloped geometry and finger elements can dynamically adjust its shape and accommodate dimensional changes, allowing the structure to absorb thermal expansion differences through elastic deformation rather than transmitting stress.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention employs a flexible ring structure with thin finger elements that can bend and deform elastically. This flexible shell design allows the coupling structure to accommodate thermal mismatch by deforming in response to dimensional changes in the high CTE component, thereby protecting the low CTE ceramic structure from excessive stress.

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If rigid coupling is used to ensure structural stability, then reliability is improved, but thermal expansion mismatch causes high strains in elevated temperature applications

Engineering Contradiction:
Improvecoupling reliabilityVSAvoidthermal strain
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The coupling structure transitions from a rigid static connection to a dynamic flexible connection. The flexure ring with scalloped geometry and finger elements can dynamically adjust its shape and accommodate dimensional changes, allowing the structure to absorb thermal expansion differences through elastic deformation rather than transmitting stress.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the mechanical parameters of the coupling structure by introducing flexibility through the flexure ring design. The scalloped geometry with finger elements provides controlled compliance, allowing the structure to change its effective stiffness and accommodate thermal expansion without compromising the integrity of the ceramic component.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If a flexible connection is used to accommodate thermal expansion, then thermal stress is reduced, but structural rigidity and stability decrease

Engineering Contradiction:
Improvethermal stressVSAvoidstructural rigidity
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The coupling structure is segmented into multiple functional zones: rigid attachment regions that provide stable mounting points for both components, and flexible intermediate regions with finger elements that accommodate thermal expansion. This segmentation allows different parts of the structure to have different mechanical properties, combining rigidity where needed with flexibility where thermal mismatch occurs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention applies local quality by making only the specific coupling region flexible while keeping the attachment regions rigid. The scalloped flexure ring introduces flexibility locally at the interface between high and low CTE components, while the overall structure maintains sufficient rigidity for stable mounting and load bearing through its geometric design and material selection.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The scalloped flexure ring effectively reduces thermal stresses between high and low CTE structures during heating and cooling cycles, preventing damage to the ceramic structure and enabling reliable coupling in elevated temperature applications.

Implementation Method 1

facilitate relative thermal expansion and contraction of the high CTE structure with respect to the low CTE structure during heating and cooling cycles

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

At least one base flexure line and at least one finger body flexure line may be provided. The base flexure line and the finger body flexure line may impart radial flexibility to the finger body of each ring finger

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2034136B1Scalloped flexure ring
Publication Date: 2015.01.14 THE BOEING CO
  • EP2034136B1 patent drawingFigure 1~2
  • EP2034136B1 patent drawingFigure 3~5
  • EP2034136B1 patent drawingFigure 6~7

AI summary

A scalloped flexure ring. An illustrative embodiment of the flexure ring includes a ring body (2) having a first ring body edge (2a) and a generally scalloped second ring body edge (2b) and a plurality of spaced-apart ring fingers (3) provided in the second ring body edge.